Conventionally, as a sunroof apparatus for a vehicle, a sunroof apparatus for a vehicle described in Patent document 1 is known, for example. A movable panel of this sunroof apparatus for a vehicle is linked to a sliding member driven by an electric motor to move in a front-and-rear direction of a vehicle. As the sliding member moves relative to the movable panel, a tilt operation is performed, and as the movable panel and the sliding member move integrally with each other, a posture is maintained. At the most front position of a movable range which mechanically restricts the sliding member from moving, between the movable panel and the sliding member, a check mechanism (an engagement and disengagement switch mechanism) is interposed which switches alternately between a state where the sliding member is movable relative to the movable panel and a state where the movable panel and the sliding member are movable integrally with each other. A state of the check mechanism when the sliding member is movable relative to the movable panel is referred to as “a disengaged state” and a state of the check mechanism when the movable panel and the sliding member are movable integrally with each other is referred to as “an engaged state”.
FIG. 7 is an explanation diagram of the check mechanism of the Patent document 1 which is developed in a circumferential direction for explaining an operation of the check mechanism. As illustrated in the diagram, the check mechanism is configured to include a rotary cam 91 and a fixed cam 92. The rotary cam 91 is supported to be movable integrally with the movable panel in a front-and-rear direction of a vehicle in a state where the rotary cam 91 allows the movable panel to perform a tilt operation, and is rotatable bout an axis line extending in the front-and-rear direction. The fixed cam 92 is supported by a sliding member at a rear side of the vehicle relative to the rotary cam 91 to be substantially coaxial with the rotary cam 91.
The rotary cam 91 includes rotary cam teeth 91a each of which includes a substantially isosceles trapezoid shape of which the long side and the short side extend in the front-and-rear direction of the vehicle. The rotary cam tooth 91a extends in a range of an angle (45 degrees) which is smaller than a predetermined angle (90 degrees in the embodiment) in a circumferential direction centered on the axis line of the rotary cam 91.
On the other hand, the fixed cam 92 includes a first fixed cam 93 and a second fixed cam 94 which are overlapped with each other in the front-and-rear direction of the vehicle. Plural fixed cam teeth 93a, each of which includes a substantially triangular tooth shape, are formed at a front end portion (an opening end portion) of the first fixed cam 93 so to be arranged about an axis line of the first fixed cam 93 at every predetermined angle (90 degrees) so as to protrude and recess in the direction of the axis line. Open portions 94a communicating along a direction of an axis line of the second fixed cam 94 are formed, as a pair, at an inner peripheral portion of the second fixed cam 94 so as to face in a radial direction (that is, at every 180 degrees). A rear end portion of each of the open portions 94a at the upper side when viewed in the diagram forms a guide portion 94b inclined to be gradually widened towards a rear end. The open portion 94a communicating over the entire length of the second fixed cam 94 in the direction of the axis line extends in a range of the same angle (45 degrees) as the rotational cam tooth 91a in the circumferential direction centered on the axis line of the fixed cam 92, and the open portion 94a including the guide portion 94b extends in the range of the predetermined angle (90 degrees) in the circumferential direction.
Further, at a rear end portion (an opening end portion) of the second fixed cam 94, engagement portions 94c are formed, as a pair, between the open portions 94a in the circumferential direction so as to be inclined towards a front side of the vehicle as they go from the open portions 94a towards the guide portions 94b. Each of the engagement portions 94c extends in the range of the predetermined angle (90 degrees) in the circumferential direction about the axis line of the fixed cam 92. Both apexes of the fixed cam tooth 93a at which the fixed cam tooth 93a changes the direction in the front-and-rear direction face, in the front-and-rear direction, a circumferentially intermediate portion of the corresponding engagement portion 94c. 
In a state where the rotary cam 91 and the fixed cam 92 are separated from each other in the front-and-rear direction of the vehicle, the rotary cam teeth 91a are at an advancement and retraction rotary position which coincides with an angular position of the open portions 94a. Thus, when the fixed cam 92 moves towards the front side of the vehicle relative to the rotary cam 91 in this state, the rotary cam teeth 91a pass the open portions 94a, and are pushed by the fixed cam teeth 93a, and accordingly rotate. Thereafter, when the fixed cam 92 moves towards the rear side of the vehicle relative to the rotary cam 91, paths for the rotary cam teeth 91a to advance to the fixed cam teeth 93a (paths to retract from the fixed cam teeth 93a) are blocked by the engagement portions 94c. Accordingly, the check mechanism comes to be in an engaged state in which the movable panel and the sliding member are movable integral with each other.
On the other hand, in the engaged state of the check mechanism when the fixed cam 92 moves towards the front side of the vehicle relative to the rotary cam 91, the rotary cam teeth 91a are pushed by the fixed cam teeth 93a, and thus rotate. Thereafter, when the fixed cam 92 moves towards the rear side of the vehicle relative to the rotary cam 91, the rotary cam teeth 91a are guided and rotated by the guide portions 94b so as to reach the advancement and retraction rotary position while the paths for the rotary cam teeth 91a to advance to the fixed cam teeth 93a (the path to retract from the fixed cam teeth 93a) are opened by the open portions 94a. Accordingly, the check mechanism comes to be in a disengaged state in which the sliding member is movable relative to the movable panel.